Check for presence of /tmp/net-${device}.conf before sourcing it [Clo…

…ses: issue1196]

Quoting Marc from issue1196:

| in recent busyboxes, sourcing a non-existent file makes busybox
| (silently?) exit, which in case of scripts/live leads to an immediate kernel
| panic since the root fs is not yet mounted.

Thanks: Marc 'Zugschlus' Haber for the bugreport and debugging this issue

debian/patches/27_support_static_ip.patch

@@ -79,7 +79,7 @@
  	fi
 
  	# split args of ethdevice=eth0,eth1 into "eth0 eth1"
-@@ -374,38 +397,27 @@
+@@ -374,38 +397,29 @@
  		devlist="$devlist $device"
  	done
 
@@ -110,7 +110,9 @@
 -			export DEVICE="$dev"
 -			break
 +		IPV4ADDR="0.0.0.0"
-+		. /tmp/net-${device}.conf
++		if [ -e "/tmp/net-${device}.conf" ]; then
++			. /tmp/net-${device}.conf
++		fi
 +		if [ "${IPV4ADDR}" != "0.0.0.0" ]; then
 +			export DEVICE="$dev $DEVICE"
 +			# break  # exit loop as we just use the irst